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贵州龙场渡槽是我国目前最大的拱跨渡槽,其脉动风频率特性分析对设计工作具有极其重要的指导作用。计算了龙场渡槽在有水、无水工况下的前20阶自振频率,分析了相应的振型;采用极值Ⅰ型概率分布函数,计算得到龙场渡槽所在地的50年一遇最大设计风速为17.6m/s;针对1986～2010年间的3次强风风速和50年一遇最大设计风速,计算了龙场渡槽所在地典型高程处的脉动风功率谱密度。研究表明:在同一高度,随着年平均最大风速的增加,功率谱密度最大值逐渐增大,其对应的频率也在增大;对于同一风速,随着高度的增加,功率谱密度的最大值逐渐增大,其对应的频率也在增大。通过比较龙场渡槽自振频率与脉动风功率谱密度显著值所对应的频率,认为龙场渡槽在上述风速下不会发生共振现象。
Longchang Aqueduct, Guizhou Province, is currently the largest arch-span aqueduct in China. The analysis of the frequency characteristics of pulsating wind plays an extremely important guiding role in the design work. The natural frequencies of the first 20 stages of Longtian Aqueduct under the condition of water and no water are calculated and the corresponding mode shapes are analyzed. Using the extreme value Ⅰ probability distribution function, the maximum 50-year maximum of aqueduct is obtained The designed wind speed is 17.6m / s. For the three strong winds from 1986 to 2010 and the maximum design wind speed in 50 years, the power spectral density of the fluctuating wind at the typical elevation of Longtian aqueduct is calculated. The results show that at the same altitude, with the increase of the annual average maximum wind speed, the maximum power spectral density gradually increases and its corresponding frequency also increases. For the same wind speed, with the increase of the altitude, the maximum power spectral density Gradually increased, its corresponding frequency is also increasing. By comparing the frequencies of the natural frequencies of Longtian aqueduct with the significant values of the power spectral density of pulsating winds, it is considered that the Longtian aqueduct will not resonate at the above wind speed.